Information about the interior of the object being examined can be obtained by way of image recordings such as these which, in particular, are slice images of different spatial positions of an object. The image recordings may, for example, be obtained by an X-ray computed-tomography scanner, a magnetic resonance imaging scanner, a photon-emission computer-tomography scanner, a positron-emission scanner, or an ultrasound appliance. By way of example, the image recordings can be used to obtain valuable information about the position, the size and the structure of internal organs, of bone tissue or of other soft tissue parts in a patient. In particular, the sequential slice images can also be converted to a three-dimensional display.
The contrast in the images produced of the object, for example of a patient, is created by locally different excitation, absorption, reflection or emission characteristics of the materials being examined with respect to the radiation, particle bombardment or sound waves used by the imaging appliance. In the case of an X-ray appliance, the different absorption or attenuation characteristics of different types of tissue are used to provide contrast. Since, for example, the characteristics of bone tissue and soft tissue parts differ widely, it is possible to analyze the structure of a bone inside the body of a patient on the basis of the contrast associated with this in the images.
Organs or vessels whose characteristics do not differ significantly in order to form contrast with the surrounding tissue in the recorded images cannot be examined in the conventional manner, because the resulting contrast is too low. For this reason, when examining an organ through which blood is flowing, for example a heart, a liver or a vessel in the area of the patient's extremities, a contrast agent is added to the blood circulation of the patient before the start of image recording. The contrast agent results in the organs being examined being imaged with sufficiently great contrast in comparison to the surrounding tissue.
A contrast agent protocol is created for this purpose, and is used to set an injection pump with the contrast agent. By way of example, the contrast agent protocol includes the nature, the volume, the concentration and the flow rate of the contrast agent. In particular, a contrast agent protocol may include a plurality of different feed phases, which differ in the parameters. In complex contrast agent protocols, phases in which, for example, a saline solution is supplied can also be provided between phases in which contrast agent is being fed, can also be provided.
The contrast agent protocol is used to produce a predictable contrast agent profile in the patient, so that the respectively required contrast agent concentration for contrast formation is produced in the examination area while the successive slice images are being recorded.
In general, the contrast agent protocol is not optimized for the individual patient in the clinical routine, since the procedures are kept simple. The patient therefore receives a suboptimum amount of contrast agent, which leads either to an undesirable excess amount, or to an adverse effect in the image quality. Furthermore, the contrast agent protocol is not always matched to a scan protocol for the imaging appliance, which leads to the contrast agent that has been supplied not being in the examination region at the time of image recording, but being there too early or too late.
Some of the parameters which are required to calculate an individual contrast agent protocol, such as the required amount of contrast agent, can be determined accurately only with the aid of image recordings. The contrast agent is therefore drawn into the injection pump only during the examination, thus making the procedure worse, and lengthening the examination time.